The invention is based on a method for displaying maneuvering room as generically defined by the preamble to the main claim. From German Patent DE 43 36 288 C1, a device for monitoring the space at the rear or front of a motor vehicle as it is being parked is known, in which especially the space at the rear of a motor vehicle being parked is monitored with a camera disposed on the rear part of the vehicle. The camera is connected via a connecting line to a viewing and monitoring device within view of the vehicle driver, so that he can observe the space behind the vehicle. The screen of the viewing and control device is subdivided into fields or quadrants. The camera focuses sharply on obstacles within the picture angle covered. By observing the viewing and control device, the driver can now avoid the obstacles shown on the screen.
The method according to the invention having the characteristics of the main claim has the advantage over the prior art that a vehicle driver is shown which maneuvering course the vehicle under his control will take if the steering angle is unchanged, because the maneuvering course to be expected if the steering angle is unchanged is incorporated into the picture of the maneuvering space at the rear. If there are no obstacles at all within the maneuvering course shown, then the driver can drive backward without having to make any further steering motions and without striking any obstacle. If there are obstacles within the maneuvering course shown, then the vehicle driver can correct the actual steering angle even as he begins to drive slowly, until the maneuvering course to be expected has shifted enough that there is no longer any obstacle within the maneuvering course. If even with a maximum turn of the wheel the driver fails in having all the obstacles located outside the maneuvering course shown, then he will generally not be able to circumvent the obstacle directly. The vehicle is at too unfavorable an angle, too close to the obstacle behind it. The driver can accordingly increase the distance from the obstacle and begin a new attempt at circumventing the obstacle. In other words, the driver can decide directly whether circumventing the obstacle requires correcting the steering angle, or whether a correction he makes is sufficient to circumvent the obstacle. He no longer has to rely only on his subjective assessment of the maneuvering course of the vehicle. On the one hand this can save the time needed for unsuccessful attempts at circumvention resulting from an incorrect assessment by the driver of the location of the vehicle relative to the obstacle. On the other hand, accidents that might be caused by the driver because of an incorrect assessment of the location of the obstacle relative to the vehicle can be avoided.
By the provisions recited in the dependent claims, advantageous refinements of the method disclosed in the main claim are possible. It is especially advantageous to ascertain the steering angle of the vehicle from the actual steering angle of the vehicle steering. Compared to ascertaining that steering angle from the wheel status, for instance, this offers the advantage that especially in vehicles with power steering, electronic detection of the steering angle is sometimes already done, and thus joint use can be made of existing electronic components.
It is also advantageous that in addition to a maneuvering course to be expected if the steering angle is unchanged, the maximum range within which a possible maneuvering course can be located is also displayed. This maximum range is defined by the maximum turn angle of the steering to the left and right. From the display of the maximum range, the vehicle driver can see directly whether with a maximum turn of the steering he can circumvent an obstacle without first making this maximum turn himself. Thus the driver of the vehicle can decide directly whether an obstacle can still be circumvented by a suitable choice of a steering angle, or whether a new attempt should be made from a greater distance and with an approach at a more-favorable angle.
It is also advantageous, along with the portion of the maneuvering space at the rear that is detected by a camera, to detect at least part of the vehicle bumper as well. This serves as a reference point to the driver for where his vehicle is located relative to obstacles displayed, and thus makes orientation additionally easier for him.
It is also advantageous for distortion caused by a camera lens in the ascertained picture to be suppressed by a processor. As a result of this distortion suppression, annoyance to the driver from picture distortion, which ensues especially in the peripheral area of the picture with extreme wide-angle lenses, is avoided. This is because distortion may cause the driver to assess the location of the vehicle incorrectly relative to obstacles displayed.
It is also advantageous that an output signal of the camera is triggered as a function of the brightness, or in other words the intensity of the received light signals, via a nonlinear characteristic curve and in particular a logarithmic characteristic curve. This offers the advantage that the camera can be used over a wide brightness range, and thus the method of the invention can be used even under very low-light conditions as well as very bright light conditions.
It is furthermore advantageous for the display of the picture of the maneuvering space at the rear to be performed in a freely programmable multipurpose instrument. Since this kind of freely programmable multipurpose instrument as a rule has a screen, the display of the picture of the maneuvering space at the rear can be made if needed in a portion of the multipurpose instrument, making it possible to dispense with an additional display in the vehicle.
It is furthermore advantageous to embody an apparatus for performing the method for displaying maneuvering room that has a central control unit. The display and the camera, and in particular the brightness, focus and picture-taking angle of the camera, can be coordinated by means of this control unit. It is also advantageous that the control unit is connected to an input by way of which the display of the possible maneuvering room, or the maneuvering course to be expected if the steering angle is unchanged, can be deactivated, for instance if merely observation of the maneuvering space at the rear is desired while the vehicle is stopped, without any intent to drive.